I'm looking for a way to do a very specific task in Calibre but maybe it's not the right software.

I know there are plugins/functionality to automatically collect metadata for existing ebooks and to get information for fields such as Author, Title, Year of publication, Tags, all based on information taken from the file's name.

Is there a plugin/way for Calibre to scrape a bit of the book and try to match it's contents with some book through some search engine? Basically I want it to automatically scrape metadata without being constrained to the file name.

calibre reads all this metadata from the book - what extra are you after
– user151019Aug 22 '15 at 14:16

@Mark I want something a bit more complex such as taking excerpts from the ebook's text and trying to match it with known books or like trying to search the book for an ISBN value and then searching for the metadata related to that ISBN
– besnicoAug 24 '15 at 20:34

The ISBM of the book should be in the metadata so no need to search
– user151019Aug 24 '15 at 20:42

@Mark most of them don't, hence the necessity
– besnicoAug 24 '15 at 22:31

@Mark You seem not to have actually looked inside many epubs of older books. Heck, most of my pre-1990 dead tree books don't have ISBNs in them (book club editions), but very few epubs that have been made from back catalogs, and of course standards-wise a huge number of modern self-published ebooks are laughable. There could be any number of reasons why the full metadata isn't available.
– AuspexFeb 29 '16 at 15:36